From his corner office on the 23rd floor of the Barclays building at Canary Wharf, David Higgins can't see the 252 hectares of earthworks and spoil-heaps in the lower Lea valley that are to become London's 2012 Olympic Park. His view faces south-east, towards the genteel slopes of Greenwich Park, to be the site of the games' equestrian events and one of the few venues Higgins does not need to build from scratch.

The Olympic Park may be out of sight but it is seldom out of mind. As chief executive of the Olympic Delivery Authority (ODA), Higgins is responsible for delivering the park on time - a non-negotiable - and inside the £9.3bn public funding package.

A wall-planner in his office leaves little room for doubt about the scale of the project or the tightness of the deadlines. Running from 2007 to 2012, it details the design, construction and overlay schedule for each individual project, from the "big five" venues (the main stadium, aquatic centre, velodrome, athletes' village and media centre) to the infrastructure - including building an electricity sub-station, burying miles of power lines underground and constructing numerous roads and bridges.

It is a sign of his and his team's optimism that the only coloured row on the calendar beyond June 2011 is the one indicating landscaping work in the park.

"Yup, by then they'll just be clipping the grass and making sure the sprinklers are turned on, while we sit back and file our nails," says Higgins.

The chief executive's levity speaks volumes about the more relaxed mood in the ODA since the turn of the year.

But the lesson of every previous games suggests the reality could be very different. In Athens in 2004 saplings were still being planted around the main stadium two days before the opening ceremony. Most were dead before the games closed, clear evidence of the later impact of early delays. By contrast, in Beijing last spring I watched landscaping teams watering already well-established trees on the approaches to the "Bird's Nest" stadium. Given that beautification is the last thing on any construction timetable, landscaping is a good indicator of a project's past.

Higgins, who oversees a team of 500 in Canary Wharf and a construction staff that will exceed 4,000 people, is determined London's experience will be closer to the Chinese example than the Greek. He is convinced that decisions now will have a fundamental impact on the cost and delivery.

"There has been a huge debate about cost, but cost is always an outcome," he says. "Much of it becomes inevitable from decisions you make early on in a project. Hitting the milestones on planning, on cost-planning, start date on site, those are the biggest ways of 'de-risking' the project. If you stuff it up at the front then it's inevitable that you are going to overspend at the end, because there's nothing else you can do."

Stuff-ups

Higgins, an Australian whose qualifications to run a huge London project were established as chief executive of the regeneration agency English Partnerships, is certain he and his team have thus far avoided "stuff-ups". Yesterday the ODA published a detailed breakdown of progress and deadlines on each budget. He hopes it will allow the public to hold the project to account and will motivate his team to hit their targets.

The willingness to publicise crucial deadlines is evidence of the mood in the ODA since the start of 2008, an Olympic year. There will be tough times between now and 2012 but the project is unlikely to face a more challenging year than 2007.

Central to the stress was wrangling over the final budget. The original bid budget was hopelessly inaccurate, predicting a mere £2.4bn for building venues with another £1bn for "legacy" and infrastructure. He will not admit it but Higgins knew it was a wild underestimate the moment he walked into the job in January 2006. "It's easy, relatively, to work out the budget and a realistic contingency," he says, a telling observation given that the original budget contained no contingency at all.

Higgins spent his first 15 months in the job mired in developing a new budget and the political wrangling necessary to reach the new figure, the £9.3bn announced in March last year, all but £1bn of which is Higgins's responsibility. Add the numerous steps required to prepare the park for construction and it is little wonder that his patience occasionally appeared stretched during public appearances last year.

"It would be fair to say that 2007 was a tough year across the board because of all the speculation on the budget. That was inevitable, I suppose, but we also had some pretty big things to get through," he says.

"We had the compulsory purchase order [for the site], which everyone assumes was just going to happen but could have faced legal challenges and appeals. There were road closures, utility cut-offs, securing vacant possession and getting the hoardings up round the site, getting the planning application through, completing the tunnelling project to underground the power lines, as well as a lot of the redesign work on the aquatic centre and the main stadium. After all that, getting into 2008 felt like a holiday.

"It was a really testing and tiring year for everyone involved but at the end of it we were able to look back and say a hell of a lot has been achieved, and we can look forward to 2008 with confidence. If I look more relaxed it's because a lot of big things have happened that were pretty demanding on the team."

If Seb Coe supplies London 2012's charm, and Paul Deighton, head of the organising committee, provides the commercial nous, Higgins is the details man, proud of his ability to compress the complexities of the project into language others can cope with. He was managing director of Lend Lease Group, the firm that built Sydney's Olympic park and is to construct London's athletes' village.

"I would hope that one of the things I can do well is look at a complex issue and turn it into something that is simpler," he says. He flourishes three sheets of A4 on to which he has compressed the key issues concerning the fiendishly complex deal for construction of Stratford International station and the shopping village adjoining the Olympic site.

"At a board dinner I half-joked that I could compress all the details of that contract and background on three sides of A4," he says. "That is a challenge that I enjoy. To be able to take a mountain of documentation, compress it and be able to put them to a board and direct them to the issues they need to focus and concentrate on, I do enjoy that."

Communicate

One of his biggest challenges is to coordinate not just the construction project but the numerous stakeholders, from local and regional government to the International Olympic Committee.

"The challenge of this job is that there are so many moving parts that if everyone is sitting in separate boxes and then trying to communicate with each other you are bound to miss something.

"I said that everyone who needs to be involved in this project should move into this building and be involved in the meetings they need to be at. The result is a relatively harmonious relationship with the organising committee.

"There have been challenging discussions over money, but we like each other, respect each other and recognise that we have different shareholders."

His grasp of detail appears to spread confidence. One senior figure at the organising committee said: "It's immensely reassuring when you ask David a question about a complex issue, because it is usually apparent that he has already thought of it and is halfway to a solution."

Higgins is confident that the sight of buildings emerging from the ground this year will boost faith in the project, and is confident the market slowdown could work in his favour. The glut of big projects in the south of England was thought to have worked against London 2012 but Higgins insists he has secured competitive contracts.

"There's a lot of uncertainty [in the market] but I believe the slowdown means there will be more competition for our tendering process. We've got good prices and great organisations involved. I'm convinced that in six to nine months' time we'll have a who's who of the construction industry in the UK on site."

While Higgins confesses to being regularly astounded by the scale of the project, there is no sign he finds it overwhelming.

"Sometimes it can keep you awake at night ... There's no point in worrying about things you can't control, but things that you can do as an individual, things you can do better or to rectify a problem, wrestling with a problem, that can keep you awake. But I'm not kept awake by this at the moment."

1985-2003 Lend Lease Group in Australia, an international property and construction company. Appointed managing director and chief executive in 1995. Developments include the Sydney Olympic Park and Bluewater Shopping Centre, Kent

2003-05 Chief executive of English Partnerships, the government national regeneration agency